Primer preactivation of peptidoglycan polymerases

Peptidoglycan glycosyltransferases are highly conserved bacterial enzymes that catalyze glycan strand polymerization to build the cell wall. Because the cell wall is essential for bacterial cell survival, these glycosyltransferases are potential antibiotic targets, but a detailed understanding of their mechanisms is lacking. Here we show that a synthetic peptidoglycan fragment that mimics the elongating polymer chain activates peptidoglycan glycosyltransferases by bypassing the rate-limiting initiation step.     

Comparison of two-dimensional periodic arrays of convex and concave nanostructures for efficient SERS templates

We describe the optical power enhancement on the surface of the 2D (two-dimensional) periodic arrays of convex and concave gold nanostructures for comparing the characteristics of the nanostructures for surface-enhanced Raman spectroscopy (SERS) templates. The optical power enhancement is due to the surface plasmon polaritons, which is calculated by the Finite-Difference Time-Domain (FDTD) method at commercially-available 532 nm pump light. A periodic array of closely-packed gold particles is defined as convex nanostructure, while a periodic array of hemispherical holes, or voids, on gold substrate is defined as concave nanostructure. The peak power enhancement factor, the average power enhancement factor and the activity rate of each structure were compared. The convex nanostructures show a strong enhancement factor in localized hotspots, while the concave nanostructures show not only the peak power enhancement factor comparable to that of convex nanostructures, but also higher spatially-averaged power enhancement factors and activity rates than those observed on the convex nanostructures, meaning that the highly enhanced near-field zone distributes densely on the substrate. We also revealed the dependence of the void diameter on the inter-void distance for the power enhancement in the concave nanostructures system, providing a guideline for the fabrication of the efficient SERS template, which shows a strong power enhancement factor with a high area density.     

Spin-polarization of radioactive 123Ing.s. by the tilted-foil method

A spin-polarized radioactive ¹²³In (I ^π , g = 1.220(2) , T _1/2 = 5.97(5) s) beam has been successfully generated by the tilted-foil method. This nuclide is the heaviest ever polarized in its ground state by this method. Using the ISOL-based re-acceleration-type facility TRIAC, an ¹²³In_g.s. beam of 305 keV/nucleon went through a stack of 15 carbon foils with a tilt angle of 70^° , and an asymmetry of 0.76 ± 0.25% of β-decays was observed by the β-NMR technique. The asymmetry shows that the tilted-foil method combined with a re-acceleration facility is useful for producing spin-polarized beams for applications such as nuclear physics and materials science.     

Randomly-grown high-dielectric-constant ZnO nanorods for?near-field enhanced Raman scattering

We investigate the dependence of the size parameter in the Mie scattering theory on the near-field enhanced Raman scattering properties for high dielectric constant ZnO nanorods grown randomly by PLD (pulsed laser deposition). High Raman signals of Rhodamine 6G (R6G) at 532 nm excitation wavelength were observed with nanorods of 400 nm average diameter. This experimental result was explained theoretically by the size parameter described in the Mie scattering theory, not by surface plasmon polaritons. This was also confirmed by the near-field distribution calculated by the FDTD (Finite-Difference Time Domain) method. The ZnO nanorods with 400 nm average diameter can detect as low as 1 μM of R6G. This near-field enhancement factor is equivalent to that with 10-nm-thick gold-coated ZnO nanorods (nanoshells) with an average core diameter of 100 nm. Controlling the diameter of bare ZnO nanorods is effective for obtaining large enhancement factors without an additional process of gold thin film coating on them.     

Adaptive SOR methods based on the Wolfe conditions

Numerical Algorithms - Because the expense of estimating the optimal value of the relaxation parameter in the successive over-relaxation (SOR) method is usually prohibitive, the parameter is often...     

Columnar Stacking of Partially Fluorinated [4]Helicenes: C−H⋅⋅⋅F Interactions Change the Stacking Orientation

The partial fluorination of polycyclic aromatic hydrocarbons often produces a layered crystal packing, where fluorinated aromatic surfaces are stacked over nonfluorinated aromatic surfaces. Herein, we report the synthesis and crystal packing of partially fluorinated [4]helicenes with steric congestion resulting from H and F atoms in the fjord region. F₆‐[4]Helicene forms head‐to‐tail columnar stacks consisting of an alternate arrangement of perfluorinated and nonfluorinated naphthalene moieties. With decreasing fluorine content, aromatic stacking switched from arene?fluoroarene (Ar^H?Ar^F) hetero‐stacking to Ar^H?Ar^H/Ar^F?Ar^F homo‐stacking with the help of intermolecular C?H???F contacts in the fjord region. As a result, head‐to‐head columnar stacks appear. Therefore, the conventional Ar^H?Ar^F stacking motif is not always applicable to F_n‐[4]helicenes with twisted π‐surfaces.     

Optical testing of star sensor (I): Defocus spot measuring technique for ground-based test

We developed a technique for measuring the intensity distribution of a point image in sub-pixel resolution even after assembly of a lens and an image sensor, which is especially suitable for defocus adjustment of a star sensor used to determine the attitude of a spacecraft. The star sensor optical system is usually aligned in a defocused position to calculate the luminance centroid of a star image in sub-pixel resolution. In the measurement technique, the point image is carefully scanned around a certain pixel on the image sensor, and the intensity change of the pixel is recorded during the scanning. We applied this technique to the alignment of our star sensor’s optical system, and we were able to suppress the spot size in a range between 1.2 and 2.2 pixels at 1/e² diameter at a certain defocus position, making it appropriate for luminance centroid calculation.     

Tokai Radioactive Ion Accelerator Complex (TRIAC)

An ISOL-based radioactive nuclear beam (RNB) facility, Tokai Radioactive Ion Accelerator Complex (TRIAC), has been jointly developed by High Energy Accelerator Research Organization (KEK) and Japan Atomic Energy Agency (JAEA). The facility started to supply RNBs for experiments in 2005 and RNBs including fission fragments with energies up to 1.1MeV/A are available in the present. Several experimental studies were performed successfully using ⁸Li beams with various energies.     

Molekulargewichtsbestimmung und Fraktionierung von Poly(L-histidin) durch Gelfiltration

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